<template>
  <div class="cart-box">
    <!-- 公用头部 -->
    <custom-header :title="'购物车'" :noback="true"></custom-header>
    <!-- 所选商品主题 -->
    <div class="cart-body">
      <!-- 多选框组，groupChange方法监听 van-checkbox 的变化，result为所选的商品id的数组-->
      <van-checkbox-group
        @change="groupChange"
        v-model="result"
        ref="checkboxGroup"
      >
        <!-- vant提供的cell组件 -->
        <van-swipe-cell
          :right-width="50"
          v-for="(item, index) in list"
          :key="index"
        >
          <div class="good-item">
            <!-- name返回给groupChange？？ -->
            <van-checkbox :name="item.cartItemId" />
            <!-- 图片通过全局过滤 -->
            <div class="good-img">
              <img :src="$filters.prefix(item.goodsCoverImg)" alt="" />
            </div>
            <div class="good-desc">
              <div class="good-title">
                <!-- 商品名称 -->
                <span>{{ item.goodsName }}</span>
                <!-- 商品数量 -->
                <span>x{{ item.goodsCount }}</span>
              </div>
              <div class="good-btn">
                <!-- 商品单价 -->
                <div class="price">¥{{ item.sellingPrice }}</div>
                <!-- 计步器，async-change实现异步技术 -->
                <van-stepper
                  integer
                  :min="1"
                  :max="5"
                  :model-value="item.goodsCount"
                  :name="item.cartItemId"
                  async-change
                  @change="onChange"
                />
              </div>
            </div>
          </div>
          <!-- 设置滑动删除，当系那个左滑动时，左侧出现“删除”按钮 -->
          <template #right>
            <van-button
              square
              icon="delete"
              type="danger"
              class="delete-button"
              @click="deleteGood(item.cartItemId)"
            />
          </template>
        </van-swipe-cell>
      </van-checkbox-group>
    </div>
    <!-- 提交组件，专门用于电商购物车提交 -->
    <van-submit-bar
      v-if="list.length > 0"
      class="submit-all van-hairline--top"
      :price="total * 100"
      button-text="结算"
      @submit="onSubmit"
    >
      <van-checkbox @click="allCheck" v-model:checked="checkAll"
        >全选</van-checkbox
      >
    </van-submit-bar>
    <!-- 当购物车没有商品时，显示空状态 -->
    <div class="empty" v-if="!list.length">
      <img
        class="empty-cart"
        src="https://s.yezgea02.com/1604028375097/empty-car.png"
        alt="空购物车"
      />
      <div class="title">购物车空空如也</div>
      <van-button round color="#1baeae" type="primary" @click="goTo" block
        >前往选购</van-button
      >
    </div>
    <nav-bar></nav-bar>
  </div>
</template>

<script>
import { reactive, onMounted, computed, toRefs } from "vue";
import { useRouter } from "vue-router";
import { useStore } from "vuex";
import { Toast } from "vant";
import NavBar from "components/NavBar.vue";
import CustomHeader from "components/CustomHeader.vue";
import { getCart, deleteCartItem, modifyCart } from "service/cart";
export default {
  components: {
    CustomHeader,
    NavBar,
  },
  setup() {
    const router = useRouter();
    const store = useStore();
    const state = reactive({
      list: [], //购物车商品列表
      result: [], //商品多选数组
      checkAll: true, //是否全选
    });

    onMounted(() => {
      initData();
    });

    const initData = async () => {
      // 进入购物车页面，加载数据动画
      Toast.loading({ message: "加载中...", forbidClick: true });
      const { data } = await getCart({ pageNumber: 1 });
      state.list = data;
      // 默认全部选中，将data中的cartItemId通过map方法制作成数组，如[1,2,3,4]
      state.result = data.map((item) => item.cartItemId);
      Toast.clear(); //取消动画
    };

    // 计算总价
    const total = computed(() => {
      let sum = 0;
      let _list = state.list.filter((item) =>
        state.result.includes(item.cartItemId)
      );
      _list.forEach((item) => {
        sum += item.goodsCount * item.sellingPrice;
      });
      return sum;
    });

    const goBack = () => {
      router.go(-1);
    };
    const goTo = () => {
      router.push({ path: "/home" });
    };

    // 当计步器变化时触发
    const onChange = async (value, detail) => {
      if (value > 5) {
        showFailToast("超出单个商品的最大购买数量");
        return;
      }
      if (value < 1) {
        showFailToast("商品不得小于0");
        return;
      }

      // 如果改变后的商品数量和改变前的商品数量相同，则不再往下执行
      if (
        state.list.filter((item) => item.cartItemId == detail.name)[0]
          .goodsCount == value
      )
        return;
      Toast.loading({ message: "修改中...", forbidClick: true });
      const params = {
        cartItemId: detail.name,
        goodsCount: value,
      };
      // 根据购物车的单选id，改变商品数量
      await modifyCart(params);
      // 改变成功后，将对于的数量进行手动增加
      state.list.forEach((item) => {
        if (item.cartItemId == detail.name) {
          item.goodsCount = value;
        }
      });
      Toast.clear(); //取消动画
    };

    // 提交购物车的方法
    const onSubmit = async () => {
      if (state.result.length == 0) {
        Toast.fail("请选择商品进行结算");
        return;
      }
      const params = JSON.stringify(state.result);
      // 提交购物车，跳转到订单生成界面
      router.push({ path: "/create-order", query: { cartItemIds: params } });
    };

    // 删除购物车的方法
    const deleteGood = async (id) => {
      await deleteCartItem(id);
      store.dispatch('updateCart')
      initData();
    };

    // 多选框监听 change 事件
    const groupChange = (result) => {
      // 当 result 的长度等于商品列表的长度时，全选状态为true
      if (result.length == state.list.length) {
        state.checkAll = true;
      } else {
        // 否则为false
        state.checkAll = false;
      }
      // 赋值 result
      state.result = result;
    };

    // 全选状态变化方法
    const allCheck = () => {
      if (!state.checkAll) {
        state.result = state.list.map((item) => item.cartItemId);
      } else {
        state.result = [];
      }
    };

    return {
      ...toRefs(state),
      total,
      goBack,
      goTo,
      onChange,
      onSubmit,
      deleteGood,
      groupChange,
      allCheck
    }
  },
};
</script>

<style lang="less">
@import "../theme/custom.less";
.cart-box {
  .cart-header {
    .fj();
    .wh(100%, 44px);
    line-height: 44px;
    padding: 0 10px;
    .boxSizing();
    color: #252525;
    background: #fff;
    border-bottom: 1px solid #dcdcdc;
    .cart-name {
      font-size: 14px;
    }
  }
  .cart-body {
    margin: 16px 0 100px 0;
    padding-left: 10px;
    padding-bottom: 100px;
    .good-item {
      display: flex;
      .good-img {
        img {
          .wh(100px, 100px);
        }
      }
      .good-desc {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        flex: 1;
        padding: 20px;
        .good-title {
          display: flex;
          justify-content: space-between;
        }
        .good-btn {
          display: flex;
          justify-content: space-between;
          .price {
            font-size: 16px;
            color: red;
            line-height: 28px;
          }
          .van-icon-delete {
            font-size: 20px;
            margin-top: 4px;
          }
        }
      }
    }
    .delete-button {
      width: 50px;
      height: 100%;
    }
  }
  .empty {
    width: 50%;
    margin: 0 auto;
    text-align: center;
    .empty-cart {
      width: 150px;
      margin-bottom: 20px;
    }
    .van-icon-smile-o {
      font-size: 50px;
    }
    .title {
      font-size: 16px;
      margin-bottom: 20px;
    }
  }
  .submit-all {
    margin-bottom: 50px;
    .van-checkbox {
      margin-left: 10px;
    }
    .van-submit-bar__text {
      margin-right: 10px;
    }
    .van-submit-bar__button {
      background: @primary;
    }
  }
  .van-checkbox__icon--checked .van-icon {
    background-color: @primary;
    border-color: @primary;
  }
}
</style>